【二叔科技】二叔测频率的测试
要测频率先得有一个频率源吧，不太准凑合用，用blink改造一下，大概20Hz的样子吧/*
Blink
Turns on an LED on for one second, then off for one second, repeatedly.
This example code is in the public domain.
*/
// Pin 13 has an LED connected on most Arduino boards.
// give it a name:
int led = 13;
// the setup routine runs once when you press reset:
void setup() {
// initialize the digital pin as an output.
pinMode(led, OUTPUT);
}
// the loop routine runs over and over again forever:
void loop() {
digitalWrite(led, HIGH); // turn the LED on (HIGH is the voltage level)
delay(25); // wait for a second
digitalWrite(led, LOW); // turn the LED off by making the voltage LOW
delay(25); // wait for a second
}
参考了一个卖传感器的商家的代码，当年二叔买这个传感器花了40+还有运费，一直扔着没用呢
http://detail.etao.com/18934469888.htm
int pin = 8;
unsigned long duration;
unsigned long starttime;
unsigned long sampletime_ms = 5000;
unsigned long lowpulseoccupancy = 0;
float ratio = 0;
void setup() {
Serial.begin(9600);
pinMode(pin,INPUT);
starttime = millis();
}
void loop() {
duration = pulseIn(pin, LOW);
lowpulseoccupancy++;
if ((millis()-starttime) > sampletime_ms)
{
ratio = lowpulseoccupancy*1000/sampletime_ms;
Serial.print(ratio);
Serial.println("Hz");
lowpulseoccupancy = 0;
starttime = millis();
}
}
测试结果20Hz蛮准确的
改到250Hz（不一定准），测得结果249Hz，这个结果可以接受啦
更专业的频率测试，不过二叔没看懂，来自饥渴工坊
http://www.geek-workshop.com/thread-3085-1-1.html
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